1. Field of the Invention
The present invention relates to a framing structure around a door opening of a vehicle.
2. Description of the Related Art
Referring to FIG. 8, a conventional framing structure 10 around a vehicle door opening includes an outer panel 11 and an inner panel 12. A stiffening panel 13 is a reinforcing member disposed in a space closed between outer panel 11 and inner panel 12. All of outer panel 11, inner panel 12 and stiffening panel 13 are stamped steel. Outer panel 11, inner panel 12 and stiffening panel 13 are joined together by conventional spot welding. Generally, the thickness of outer panel 11 is about 0.8 mm. Outer panel 11 provides the outer appearance of the vehicle. Inner panel 12 and stiffening panel 13 each have a thickness of about 2 mm to perform the function of contributing to the frame strength of the vehicle body.
In the conventional framing structure 10, inner panel 12 and stiffening panel 13 must be formed using four to five press molds. Another disadvantage is that the conventional process generates much scrap during the manufacture of inner panel 12 and stiffening panel 13. Further, inner panel 12 and stiffening panel 13 are joined together by spot welding and their joining portions are spaced a certain distance from each other, so that the disadvantage of such construction is inferior in view of strength and stiffness.
Referring now to FIG. 9, another conventional framing structure, disclosed in Japanese Laid-open Patent Publication No. 2000-219154, includes a side structure 20 in a vehicle having an outer panel 21 and an inner closed tube 22. Inner closed tube 22 is formed by a tube hydraulic-forming process. Outer panel 21 and inner closed tube 22 are partially joined together by an inner band 23. Such partial joining is inferior in view of strength and stiffness. In addition, inner band 23 entails additional weight and an increase in the number of parts. Furthermore, in addition to joining of inner closed tube 22 and inner band 23, inner band 23 and outer panel 21 must be also joined together. Thus, the joining process must be done at least twice.
A construction similar to side structure 20 is also disclosed in Japanese Laid-open Patent Publications Nos. 2000-219153, 2000-219152 and 2000-219150.
Referring now to FIG. 10, a conventional framing structure in a vehicle, disclosed in Japanese Laid-open Patent Publication No. 2000-95146, includes a center pillar 30 consisting of an outer panel 31, an outer reinforced frame 32 and a tubular reinforced frame 33. Outer panel 31 and tubular reinforced frame 33 are joined together by way of outer reinforced frame 32. That is, outer reinforced frame 32 and tubular reinforced frame 33 are welded together. Then outer reinforced frame 32 is welded to outer panel 31. Accordingly, outer reinforced frame 32 as an intermediate means adds weight, constitutes an additional part and adds a welding process. Since outer reinforced frame 32 is disposed extensively along the entire surface of tubular reinforced frame 33, adds more weight than does side structure 20 in FIG. 9.
The above, and other objects, features and advantages of the present invention will become apparent from the following description read in conjunction with the accompanying drawings, in which like reference numerals designate the same elements.